Flash analog-to-digital (A/D) converters, so called because a converted output can be quickly provided, are well known. Flash A/D converters utilize either resistors or capacitors to develop a comparison voltage for comparison with a sampled input voltage. A plurality of comparators is used to develop an equivalent digital representation of the sampled input voltage. A common data format of the digital equivalent is known as the "thermometer" format or code because the digital representation consistently uses logic one values in all LSB least significant bit locations below the most significant one to represent every magnitude which may be represented by the format. In other words, the binary representation of thermometer format uses logic ones from left to right as the magnitude being represented increases. Because this representation is similar to the way a thermometer represents temperature, the representation is commonly referred to as thermometer in the literature.
The thermometer format is advantageous to use with flash A/D converter because of the direct proportionality associated with the A/D conversion. However, before the digital representation can be used the digital value must be converted to the common binary format. Others have converted from thermometer to binary format in one of several ways. A first known technique is to first convert from the thermometer format to an intermediate code, such as the conventional Gray code format, and then convert the intermediate code format to binary format. The first technique has the disadvantage of having to make two conversions. A second known technique is to directly convert from thermometer code to binary code. However, existing techniques to accomplish a direct conversion have a significant speed disadvantage. A most significant bit (MSB) is easy to decode from thermometer to binary. However, the conversion of least significant bits (LSBs) requires information from most of the thermometer bits. For example, a six bit flash converter requires up to six logic circuit processing delays in order to decode the least significant bit. Therefore, known digital encoders typically require a significant amount of time and/or circuitry to implement digital format conversions.